There are certain types of industrial operations which produce enormous quantites of pulverulent material. Orderly transfer of such material from the units that produce it to a transportation system presents substantial problems which are aggravated by the nature of the material which makes to inherently difficult to design systems for its orderly handling.
A severe problem is presented by the fly ash produced by the high efficiency coal burning furnaces and collected in the precipitators of electric power generating plants. A large coal burning power facility can produced many tons of fly ash an hour; and it is extremely difficult material to handle because it is about as fine as talcum powder, is very abrasive, and has a great tendency to lump and cake in hoppers and conveyors. This makes it difficult to obtain a reasonably even flow of material into a device such, for example, as a pressure-type pneumatic conveyor which is very efficient for moving pulverulent material.